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Rayovac 4.5 battery replacement hack

Fizzbinn

Well-known member
I’ve previously used a 3 AAA battery holder to replace the dead Rayovac 4.5v “Computer Clock Battery” in a couple of my Macs.

After some chat discussions I thought I’d try something different for my Performa 575, especially after noticing that in the Macintosh LC 520/550/575 Service Source doc it notes that 575 battery is good if it’s 3 volts or higher, the same as it says for the 520 & 550 which use 1/2 AA 3.6v batteries…

So why not try a CR2032!

I though of cannibalizing a @Geekybit MeowToast 1/2 AA battery Replacement (which are awesome) but found another holder on Amazon so I can keep those for Macs with the 1/2 AA holder.

AuBreey 5PCS/LOT for Arduino Lilypad Coin Cell Battery Holder CR2032 Battery Mount Module:

DEB47C21-10CF-4875-8371-B3084CE417FB.jpeg

88DBCDE5-6BBC-4E7D-AD8B-9DC0D1E2D99D.jpeg

Cracked open the Rayovac mainly since I was curious:
96225E59-2AD5-40F6-A971-2519A266002C.jpeg

Soldered the cable from the old battery to the new holder:
99F2C69D-E9AB-42E0-86B9-198A41C2C57C.jpeg

Reused the velco from the old battery too (still had stickum):
0030E1D1-59E0-4B72-A8F3-B53DA46AF78A.jpeg

575 board with 3 AAA based battery holder:
58787EDE-2FC7-4D12-B23C-2BCD74BF3DAB.jpeg

575 board with CR2032 based battery holder:
E0D94C57-BD1B-457F-BA17-0D43176145AE.jpeg

Close up pic, perhaps most importantly it works just fine!
06488B28-9B36-4E09-8190-9063FC9AEBEA.jpeg
 
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mmu_man

Well-known member
Ah yes I remember breaking into the same one some years ago… With patience and a good cutter. I think the coin cell might actually fit the original case even.
 
Hah, I replaced mine with the 3-AA holder built in to some Wal-Mart LED string lights. Just flip pop in some lithiums, flip the switch to 'On', and tape it there.
 

jessenator

Well-known member
3 volts or higher
I wonder if this is the same (mostly) across the board (I know some II-series have multiple batteries…). I've been using a 3x button cell holder (which was a terrible 3d-print object, but some heat made it work), but I've been told even those alkalines will leak.

I have some of the meowtoast adapters and would like to just use them. So if any Mac can take at least a 3V cell, do we need a 4.5V 1:1 replacement? I'm sure this question has been asked, but I can't, for the life of me, recall when/where/if it was answered.
 

Fizzbinn

Well-known member
Just so you know I am currently working on a 4.5v Battery pack option...

So if any Mac can take at least a 3V cell, do we need a 4.5V 1:1 replacement? I'm sure this question has been asked, but I can't, for the life of me, recall when/where/if it was answered.

I'm wondering the same thing. The fact that all the Apple Service source docs I've checked for Mac's with these 4.5V batteries say the same thing as those with (single) 3.6V 1/2 AA batteries, "If the battery voltage is below 3.0 V, replace the battery" makes me think that maybe the logic board requirements didn't change just the battery tech to do it.

Image 1-4-22 at 1.27 PM (1).jpeg
Image 1-4-22 at 1.49 PM.jpeg

Something like the Apple requirement is a battery that degrades to under 3V in 10 years (or some other time period that doesn't really matter for the sake of this argument).
- A lithium based 1/2 AA battery with new production voltage of 3.6V degrades to under 3V in 10 years
- But it takes an Alkaline battery with a higher new production voltage of 4.5V to degrade to under 3V in 10 years
To make the change I'm guessing the Alkaline Rayovac solution must have been cheaper or otherwise beneficial to Apple in some way.

Just a guess...
 
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Geekybit

Active member
The version I was going to go with was going to be a 3 1.5v button batteries since they are not rechargeable and will not back charge. Then a 3d printed case with the lead attached ... but seeing how it works the same as the standard Mac boards, yeah I could make a simple Meow toast version...

Keep in mind the circuit for the batteries are designed to run from a battery which means they actually have a fairly large tolerance of voltage range...

from what I understand the Mac boards don't start acting weird till 2.4-2.6v for the battery though the manual says 3.0V ... also CR 2032 say they are 3v but most actually are 3.2v out of the gate
 

Fizzbinn

Well-known member
The version I was going to go with was going to be a 3 1.5v button batteries since they are not rechargeable and will not back charge. Then a 3d printed case with the lead attached ... but seeing how it works the same as the standard Mac boards, yeah I could make a simple Meow toast version...

Keep in mind the circuit for the batteries are designed to run from a battery which means they actually have a fairly large tolerance of voltage range...

from what I understand the Mac boards don't start acting weird till 2.4-2.6v for the battery though the manual says 3.0V ... also CR 2032 say they are 3v but most actually are 3.2v out of the gate

I was trying to find some more backing on the ever truthful internet for the idea that alkaline batteries (like the Rayovac) lose voltage faster than regular, non-rechargeable, lithium batteries (like 1/2 AA and CR3032) and found this:
Sounds legit?

Also somewhere I think I read that there are Color Classic logic boards that have the connector for the Rayovac battery instead of the 1/2 AA battery holder. Anyone recall this too?

A Meow toast board with through hole solder points for a donated Rayovac battery connector seems like it could potentially serve both use cases (Soldering wires to surface pads as I did above is slightly annoying). Just my 2 cents.
 
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Geekybit

Active member
I was trying to find some more backing on the ever truthful internet for the idea that alkaline batteries (like the Rayovac) lose voltage faster than regular, non-rechargeable, lithium batteries (like 1/2 AA and CR3032) and found this:
Sounds legit?

Also somewhere I think I read that there are Color Classic logic boards that have the connector for the Rayovac battery instead of the 1/2 AA battery holder. Anyone recall this too?

A Meow toast board with through hole solder points for a donated Rayovac battery connector seems like it could potentially serve both use cases (Soldering wires to surface pads as I did above is slightly annoying). Just my 2 cents.
This is what I was thinking of sell a meow toast with a two through holes... and a bit of Velcro tape and the wires and connector since they still sell them to this day and they are cheap.
 

kahlil88

Active member
Wanted to share my very cheap solution: LR44H button cell holder (batteries included) for $3.50 (99 cents + shipping) from Mouser and I used a cable tie to hold it down.
 

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